Anti-Viral Pyrimidine Nucleoside Analogues

ABSTRACT

A compound of formula (I) wherein Ar can be one six-membered or two fused six-membered aromatic rings; R 8  and R 9  can be hydrogen, alkyl, cycloalkyl, halogen, amino, alkylamino, dialkylamino, nitro, cyano, alkyoxy, aryloxy, thiol, alkylthiol, arythiol, or aryl; Q can be O, S or CY 2 , where Y may be H, alkyl or halogen; X can be O, NH, S, N-alkyl, (CHR 2 ) m  where m is 1 to 10, and CY 2 ; Z can be O, S, NH, or N-alkyl; U″ is H and U′ can be H or CH 2;  wherein: T can be OH, H, halogen, O-alkyl, O-acyl, O-aryl, CN, NH 2  or N 3 ; T′ and T″ can be H or halogen; and W can be H or a phosphate group. Compounds show anti-viral activity, for example with respect to varicella zoster virus.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. application Ser. No. 12/889,980, filed Sep. 24, 2010, allowed, which is a divisional application of U.S. application Ser. No. 10/257,855, filed Oct. 17, 2002 (now U.S. Pat. No. 7,820,631), which is a National Stage application of International Application No. PCT/GB01/01694, filed Apr. 12, 2001, which claims the benefit of United Kingdom Patent Application GB 0009486.2, filed Apr. 17, 2000, all of said applications incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a class of nucleoside analogues and to their therapeutic use in the prophylaxis and treatment of viral infection for example by varicella zoster virus (VZV). Varicella zoster virus is the aetiological agent in chickenpox and shingles which can cause considerable human illness and suffering.

BACKGROUND OF THE INVENTION

The following references and other information are pertinent to the background of the invention:

WO 98/49177 describes a class of nucleoside analogues demonstrating anti-viral properties. A representative of the compounds disclosed in WO 98/49177 is 3-(2-deoxy-β-D-ribofuranosyl)-6-decyl-2,3-dihydrofuro [2,3-d]pyrimidin-2-one.

“Acyclovir” is a compound known to have anti-viral properties. It is described in The Merck Index 12th Edition.

BVDU is (E)-5-(2-bromo-vinyl)-2′-deoxyuridine and is described in De Clercq et al. Proc. Natl. Acad. Sci., USA 1979, 76, 2947.

G. T. Crisp and B. L. Flynn, J. Org. Chem. 1993, 58, 6614 describes palladium catalyzed couplings of terminal alkynes with a variety of oxyuridines. One coupling described is that between 5-ethynyl-2-deoxyuridine and a range of fluorinated aryl compounds.

E. V. Malakhova et al. Bioorg. Khim. (1998), 24 (9), 688-695 describes reagents for introducing a fluorescent deoxyuridine 2-phenylbenzoxazole derivative into oligonucleotides.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide a novel class of nucleoside analogues.

It is a further object of the present invention to provide a class of nucleoside analogues for therapeutic use in the prophylaxis and treatment of a viral infection, for example a varicella zoster virus (VZV).

According to the first aspect of the present invention there is provided a compound having formula I as follows:

wherein:

Ar is an, optionally substituted, aromatic ring system, the aromatic ring system comprising one six-membered aromatic ring or two fused six-membered aromatic rings;

R₈ and R₉ are each independently selected from H, alkyl, aryl, cycloalkyl, halogen, amino, nitro, thiol, cyano, alkylamino, dialkylamino, alkoxy, aryloxy, alkylthiol, and arylthiol;

Q is selected from the group comprising O, S, and CY₂, where Y may be the same or different and is selected from H, alkyl, and halogen;

X is selected from the group comprising O, NH, S, N-alkyl, (CH)_(m) where in is 1 to 10, and CY₂, where Y may be the same or different and is selected from H, alkyl, and halogen;

Z is selected from the group comprising O, S, NH, and N-alkyl;

U″ is H and U′ is selected from H and CH₂T, or U′ and U″ are joined so as to provide a ring moiety including Q wherein U′-U″ together is respectively selected from the group comprising CTH—CT′T″ and CT′=CT′, so as to provide the following ring moiety options:

wherein T is selected from the group comprising OH, H, halogens, O-alkyl, O-acyl, O-aryl, CN, NH₂, and N₃;

T′ is selected from the group comprising H and halogens and where more than one T′ is present, they may be the same or different;

T″ is selected from the group comprising H and halogens; and

W is selected from the group comprising H, a phosphate group, and a phosphonate group; with the proviso that when T is OAc and T′ and T″ are present and are H, Ar is not 4-(2-benzoxazolyl)phenyl.

It is to be understood that the present invention extends to compounds according to formula I wherein the group W is modified to provide any pharmacologically acceptable salt or derivative of H, phosphate, or phosphonate. The present invention also includes any compound which is a pro-drug of the compound according to formula (I), any such prodrug being provided by modification of the moiety W, wherein W is selected from phosphates and derivatives thereof, and phosphonates and derivatives thereof.

The aromatic ring system present in Ar may contain one, two, three or four suitable ring heteroatoms, whose position may be varied. Any ring heteroatoms present may be the same or different and can, for example, be O, S or N.

Preferably the aromatic ring system in Ar is carbocyclic. The aromatic ring system in Ar is thus preferably selected from the group comprising, optionally substituted, phenyl and naphthyl radicals. More preferably, the aromatic ring system in Ar comprises one six-membered carbocyclic ring and is thus phenyl or a substituted derivative of phenyl.

When the aromatic ring system is naphthyl or a substituted derivative of naphthyl, the naphthyl radical is preferably bonded to the nucleoside ring system at a position adjacent the fused bond in the naphthyl radical.

Preferably the aromatic ring system in Ar is substituted. Preferably the aromatic ring system in Ar is substituted by one or more moieties independently selected from the group comprising H, alkyl, aryl, and cycloalkyl, chlorine, bromine, iodine, cyano, alkylamino, dialkylamino, alkoxy, aryloxy, alkylthiol and arylthiol. Suitable moieties for use as substituents on the aromatic ring system of Ar include C₁-C₁₀ alkyl, C₃-C₁₀ cycloalkyl, C₁-C₁₀ alkylamino, C₃-C₁₀ dialkylamino, C₁-C₁₀ alkoxy, aryloxy, C₁-C₁₀ alkylthiol, and C₆-C₁₀ aryl.

Any alkyl, cycloalkyl, aryl or alkoxy substituents on the aromatic ring system of Ar may themselves be substituted. Preferably such substituents on the said alkyl, cycloalkyl, aryl and alkoxy substituents comprise one or more members independently selected from the group comprising chlorine, bromine, iodine, CN, CO₂ alkyl (C₁ to C₆), CONH₂, CONH alkyl (C₁ to C₆), SH, S alkyl (C₁ to C₆) and NO₂.

Preferably any substituent present in or on the aromatic ring system of Ar is at least substantially non-polar. Preferably any such substituent is hydrophobic.

Preferably any substituent or substituents on the aromatic ring system of the Ar comprise one or more alkoxy moieties and/or one or more, optionally substituted, alkyl moieties.

Any alkyl or alkoxy moiety present on the aromatic ring system of Ar is preferably straight chained, unsubstituted and saturated. Branched, substituted and/or unsaturated alkyl or alkoxy groups may however be employed. The term ‘alkyl’ with respect to any substituent present on the aromatic ring system thus comprises any aliphatic non-cyclic hydrocarbyl radical, including alkenyl and alkynyl. The nature, position, and number of any substituents and unsaturation may be varied.

Preferably any such alkyl or alkoxy moiety or moieties, in total, comprise 3 to 8 carbon atoms, calculated excluding any substituents that may be present on the said alkyl or alkoxy moiety or moieties. The remainder of any substituent positions on the aromatic ring system of Ar are preferably H. More preferably any alkyl moiety or moieties present on the aromatic ring system of Ar comprise, in total, from 4 to 7 carbon atoms, even more preferably from 5 to 6 carbon atoms, calculated excluding any substituents that may be present on the said alkyl moiety or moieties. More preferably any alkoxy moiety or moieties present on the aromatic ring system of Ar comprise, in total, from 3 to 7 carbon atoms, calculated excluding any substituents that be present on the said alkoxy or alkoxy moieties.

Any alkyl moiety or moieties present on the aromatic ring system of Ar is preferably selected from the group comprising C₁, C₂, C₃, C₄, C₅, C₆, C₇ and C₈ alkyl moieties and mixtures thereof, more preferably from the group comprising C₃, C₄, C₅, C₆, C₇ and C₈ alkyl moieties and mixtures thereof, even more preferably from the group comprising C₄, C₅, C₆ and C₇ alkyl moieties and mixtures thereof. Preferably an alkyl moiety or moieties is selected from the group comprising C₅ and C₆ alkyl moieties and mixtures thereof.

Where the substituent present on the aromatic ring system is an aryl moiety, it is preferably phenyl. Such aryl substituents can be substituted. Preferably any such substituents are selected from the group set out above.

Any substituent on the aromatic ring system of Ar can be at any position. Any of the meta, ortho or para positions can therefore be occupied by a substituent. Preferably any single substituent, particularly where the aromatic ring system comprises a phenyl derivative, is a para substituent with respect to the bond between the aromatic ring system and the nucleoside fused ring system. Preferably the aromatic ring system of Ar is a six-membered carbocyclic ring system and comprises one alkyl or one alkoxy substituent at the para position.

Each of R₈ and R₉ may be substituted or unsubstituted, and may be branched or unbranched as appropriate to their structure. When either of R₈ and R₉ are alkyl or cycloalkyl they may be saturated or unsaturated. The nature, position, and number of any substituents and unsaturation present may be varied.

When either of R₈ and R₉ is alkyl or cycloalkyl, suitable substituents that may optionally be present include OH, halogen, amino, CN, CO₂H, CO₂ alkyl, CONH₂, CONH alkyl, SH, S alkyl, and NO₂, wherein alkyl in a substituent is suitably C₁-C₈. Suitably, any substituent is non-polar, more suitably any such substituent is hydrophobic.

Suitably R₈ is selected from the group comprising H, C₁-C₁₀ alkyl, C₃-C₁₀ cycloalkyl, C₁-C₁₀ alkylamino, C₁-C₁₀ dialkylamino, C₁-C₁₀ alkyloxy, C₆-C₁₀ aryloxy, C₁-C₁₀ alkylthiol, and C₆-C₁₀ aryl.

Suitably R₉ is selected from the group H, C₁-C₁₀ alkyl, C₃-C₁₀ cycloalkyl, C₁-C₁₀ alkylamino, C₁-C₁₀ dialkylamino, alkyloxy, aryloxy, C₁-C₁₀ alkylthiol, and C₆-C₁₀ aryl.

Preferably each of R₈ and R₉ is a small alkyl, ie. a C₁-C₂ alkyl group, or H. More preferably, each of R₈ and R₉ is H.

Throughout the present specification, ‘halogen’ is taken to include F, Cl, Br and I. Unless otherwise stated, chlorine and bromine are preferred.

Unless otherwise stated, throughout the present specification ‘alkyl’ is taken to include C₁-C₁₀ alkyl, preferably C₁-C₅ alkyl, and saturated and unsaturated, branched and unbranched, and substituted and unsubstituted aliphatic hydrocarbyl.

Unless otherwise stated, throughout the present specification ‘cycloalkyl’ is taken to include C₃-C₁₀, preferably C₅-C₈, and saturated and unsaturated and substituted and unsubstituted cyclic aliphatic hydrocarbyl.

Unless otherwise stated, throughout the present specification ‘aryl’ is taken to include C₅-C₁₀ single ring or fused bi-ring aryl, substituted and unsubstituted aryl, and aryl containing 1 to 4 heteroatoms, which may he the same or different and may be selected from, for example, O, N and S.

Suitable substituents for ‘alkyl’, ‘cycloalkyl’ and ‘aryl’, other than when an alkyl, cycloalkyl or aryl moiety is present as a substituent on the aromatic ring system in Ar, include one or more members independently selected from the group comprising OH, halogen, amino, CN, CO₂H, CO₂ alkyl(C₁ to C₆), CONH₂, CONH alkyl(C₁ to C₆), SH, S alkyl(C₁ to C₆) and NO₂.

Preferably Q is CH₂, S, or O. More preferably Q is O. Where Q is CY₂ and includes a halogen, it is preferably F. Y is preferably H.

Preferably X is O, S, or NH. More preferably X is O. Where X is (CH)_(n), n is preferably 1 or 2, most preferably 1. Suitably, when X is N-alkyl, alkyl is C₁-C₅, and when X is CY₂, at least one Y is C₁-C₅ alkyl. Most preferably, X is O.

Preferably Z is O. Where Z is N-alkyl, suitably the alkyl is C₁-C₅.

Preferably U′ and U″ are joined to provide the saturated ring moiety including T, T′ and T″. Preferably T, T′, and T″ in such a ring moiety are respectively OH, H, and H.

Preferably T is OH. When T is halogen it is preferably F.

Preferably each of T′ and T″ is H. When either or both of T′ and T″ is halogen, it is preferably F.

When W is a moiety which renders the compound a pro-drug of the compound according to Formula (I) it is to be understood that the term pro-drug includes the corresponding free base of each of the nucleosides described.

It is also to be understood that the term ‘phosphate’ includes diphosphates and triphosphates. Hence, W includes pharmacologically acceptable salts and derivatives of phosphates, diphosphates, and triphosphates, and of phosphonates, diphosphonates, and triphosphonates. It also includes any moiety which provides a compound which is a prodrug of the compound according to formula (I), wherein W is selected from phosphates, diphosphates, and triphosphates, and derivatives thereof, and phosphonates, diphosphonates, and triphosphonates, and derivatives thereof.

Each compound of the present invention may be a pure stereoisomer coupled at each of its chiral centers or it may be inverted at one or more of its chiral centers. It may be a single stereoisomer or a mixture of two or more stereoisomers. If it is a mixture the ratio may or may not be equimolar. Preferably the compound is a single stereoisomer. The compound may be in either enantiomeric form i.e. it may be either the D or L enantiomer either as a single stereoisomer or as a mixture of the two enantiomers. More preferably the compounds has a stereochemistry resembling natural deoxy nucleosides derived from β-D-2-deoxyribose. However other enantiomers particularly the L enantiomers may be employed.

It is to be understood that the present invention extends to compounds wherein the sugar moiety and phosphate if present have either together or separately been modified as well known to a person skilled in art. For example the sugar substituent on the nucleoside may be usefully phosphonated.

It is also possible for a compound embodying the present invention to be in a sugar form as for example modified and derived from a D-xylo sugar system.

Particularly preferred compounds embodying the present invention have the following formulae:

According to a further aspect of the present invention there is provided a method for preparing compounds having Formula I above wherein a 5-halo nucleoside analogue is contracted with a terminal alkyne in the present of a catalyst. Alternatively 5-alkynyl nucleoside can be cyclized in the presence of a catalyst. Suitably the catalyst is a copper catalyst. The 5-alkynyl nucleoside has the general formula:

Compounds embodying the present invention can show antiviral activity. In particular it has surprisingly been found that compounds embodying the present invention can show antiviral activity against for example varicella zoster virus.

According to a further aspect of the present invention there is provided a compound according to the present invention for use in a method of treatment, suitably in the prophylaxis or treatment of a viral infection.

According to a further aspect of the present invention there is provided use of a compound according to the present invention in the manufacture of a medicament for the prophylaxis or treatment of viral infection.

According to a further aspect of the present invention there is provided a method of prophylaxis or treatment of viral infection comprising administration to a patient in need of such treatment an effective dose of a compound according to the present invention

According to a further aspect of the present invention there is provided use of a compound of the present invention in the manufacture of a medicament for use in the prophylaxis or treatment of a viral infection, particularly an infection with the varicella zoster virus.

According to a further aspect of the present invention there is provided a pharmaceutical composition comprising a compound of the present invention in combination with a pharmaceutically acceptable excipient.

Medicaments embodying the present invention can be administered by oral or parenteral routes, including intravenous, intramuscular, intraperitoneal, subcutaneous, transdermal, airway (aerosol), rectal, vaginal and topical (including buccal and sublingual) administration.

For oral administration, compounds embodying the present invention will generally be provided in the form of tablets or capsules, as a powder or granules, or as an aqueous solution or suspension.

Tablets for oral use may include the active ingredient mixed with pharmaceutically acceptable excipients such as inert diluents, disintegrating agents, binding agents, lubricating agents, sweetening agents, flavoring agents, coloring agents and preservatives. Suitable inert diluents include sodium and calcium carbonate, sodium and calcium phosphate, and lactose, while corn starch and alginic acid are suitable disintegrating agents. Binding agents may include starch and gelatin, while the lubricating agent, if present, will generally be magnesium stearate, stearic acid or talc. If desired, the tablets may be coated with a material such as glyceryl monostearate or glyceryl distearate, to delay absorption in the gastrointestinal tract.

Capsules for oral use include hard gelatin capsules in which the active ingredient is mixed with a solid diluent, and soft gelatin capsules wherein the active ingredient is mixed with water or an oil such as peanut oil, liquid paraffin or olive oil.

Formulations for rectal administration may be presented as a suppository with a suitable base comprising for example cocoa butter or a salicylate.

Formulations suitable for vaginal administration may be presented as pessaries, tampons, creams, gels, pastes, foams or spray formulations containing in addition to the active ingredient such carriers as are known in the art to be appropriate.

For intramuscular, intraperitoneal, subcutaneous and intravenous use, compounds embodying the present invention will generally be provided in sterile aqueous solutions or suspensions, buffered to an appropriate pH and isotonicity. Suitable aqueous vehicles include Ringer's solution and isotonic sodium chloride. Aqueous suspensions embodying the invention may include suspending agents such as cellulose derivatives, sodium alginate, polyvinyl-pyrrolidone and gum tragacanth, and a wetting agent such as lecithin.

Suitable preservatives for aqueous suspensions include ethyl and n-propyl phydroxybenzoate.

Compounds embodying the present invention can be presented as liposome formulations.

In general, a suitable dose will be in the range of 0.001 to 300 mg per kilogram body weight of the recipient per day, preferably in the range of 0.01 to 25 mg per kilogram body weight per day and most preferably in the range 0.05 to 10 mg per kilogram body weight per day. The desired dose is preferably presented as two, three, four, five or six or more sub-doses administered at appropriate intervals throughout the day. These sub-doses may be administered in unit dosage forms, for example, containing 0.1 to 1500 mg, preferably 0.2 to 1000 mg, and most preferably 0.5 to 700 mg of active ingredient per unit dosage form.

Embodiments of the present invention will now be described by way of example only.

EXAMPLE 1 Preparation of 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-propylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

To a solution of 5-(4-n-propyl-phenylacetylene)-2′-deoxyuridine (200 mg, 0.54 mmol) in methanol and triethylamine (7:3) (20 ml), was added copper iodide (20 mg, 0.102 mmol). The mixture was refluxed for 4 hours. The solvent was removed in vacuo, and the crude product as purified by flash column chromatography (initial eluent: ethyl acetate, followed by: ethyl acetate/methanol (9:1)). The combined fractions were combined and the solvent was removed in vacuo to give the crude product, which was recrystallized from methanol to give pure 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-propylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (86 mg, 43%).

¹H-NMR (d₆-DMSO; 300 MHz); 8.72 (1H, s, H-4), 7.43 (2H, H_(a)) −7.28 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.15 (1H, s, H-5), 6.18 (1H, dd, ³J=6.15 Hz, H-1′), 5.31 (1H, d, ³J=4.0 Hz, 3′-OH), 5.12 (1H, t, ³J=5.01 Hz, 5′-OH), 4.31 (1H, m, H-3′), 3.89 (1H, m, H-4′), 3.51 (2H, m, H-5′), 2.65 (2H, t, ³J=6.9 Hz, α-CH₂), 2.31 and 2.12 (2H, m, 2-H′a and 2-H′b), 1.58 (2H, sxt, CH₂, ³J=6.9 Hz), 0.85 (3H, t, ³J=6.9 Hz, CH₃). ¹³C-NMR (d₆-DMSO; 75 MHz): 13.2 (CH₃), 20.1, 22.3, (C₂H₄), 41.5 (C-2′), 62.3 (C-5′), 71.6 (C-3′), 83.2, 88.4 (C-1′, C-4′), 100.4 (C-5), 104.6 (C-4a), 125.3 (C—H_(b)), 128.4 (ipso-C), 131.8 (C—H_(a)), 141.2 (para-C), 138.5 (C-4), 154.6 (C-6), 159.1 (C-2), 172.3 (C-7a).

General Procedure for the Preparation of 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4n-alkylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one Analogues

To a stirred solution of 5-iodo-2′-deoxyuridine (800 mg, 2.26 mmol) in anhydrous dimethylformamide (8 ml), was added diisopropylethylarnine (584 mg, 0.8 ml, 4.52 mmol), the 4-n-alkyl-phenylacetylene (6.76 mmol), tetrakis(triphenylphoshine)palladium (0) (261 mg, 0.266 mmol) and copper (I) iodide (86 mg, 0.452 mmol). The mixture was stirred for 18 hours, at room temperature, under a nitrogen atmosphere, after which time tic (ethyl acetate/methanol 9:1), showed complete conversion of the starting material. Copper (I) iodide (80 mg, 0.40 mmol), triethylarnine (15 ml) and methanol (20 ml) were then added to the mixture, which was subsequently refluxed for 4 hours. The reaction mixture was then concentrated in vacuo, and the resulting residue was dissolved in dichloromethane and methanol (1:1) (6 ml), whereupon an excess of Amberlite IRA-400 (HCO3 form) was added and stirred for 30 minutes. The resin was filtered and washed with methanol, and the combined filtrate was evaporated to dryness. The crude product was purified by flash column chromatography (Initial eluent: ethyl acetate, followed by: ethyl acetate/methanol (9:1)). The appropriate fractions were combined, where the solvent was removed in vacuo, to give the pure product.

EXAMPLE 2 Preparation of 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4n-butylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The above general procedure was carried out using 4-n-butyl-phenylacetylene (1.072 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-butylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (140 mg, 16%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.76 (1H, s, H-4), 7.46 (2H, H_(a)) −7.31 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.20 (1H, s, H-5), 6.21 (1H, dd, ³J=6.15 Hz, H-1′), 5.37 (1H, d, ³J=4.0 Hz, 3′-OH), 5.31 (1H, t, ³J=5.01 Hz, 5′-OH), 4.31 (1H, m, H-3′), 3.75 (1H, m, H-4′), 3.48 (2H, m, H-5′), 2.65 (2H, t, ³J=6.9 Hz, α-CH₂), 2.31 and 2.12 (2H, m, 2-H′a and 2-H′b), 1.62 (4H, m, CH₂), 0.87 (3H, t, ³J=6.9 Hz, CH₃). ¹³C-NMR (d₆-DMSO; 75 MHz): 13.2 (CH₃), 20.1, 22.3, 27.9 (C₃H₆), 42.5 (C-2′), 63.7 (C-5′), 73.6 (C-3′), 83.5, 88.7 (C-1′, C-4′), 100.8 (C-5), 108.4 (C-4a), 125.3 (C—H_(b)), 128.4 (ipso-C), 131.8 (C—H_(a)), 141.2 (para-C), 138.5 (C-4), 154.6 (C-6), 159.1 (C-2), 170.9 (C-7a).

EXAMPLE 3 Preparation of 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-pentylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The above general procedure was carried out using 4-n-pentyl-phenyllacetylene (1.15 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-pentylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (137 mg, 15%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.81 (1H, s, H-4), 7.51 (2H, H_(a)) −7.35 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.18 (1H, s, H-5), 6.23 (1H, dd, ³J=6.15 Hz, H-1′), 5.37 (1H, d, ³J=4.0 Hz, 3′-OH), 5.31 (1H, t, ³J=5.01 Hz, 5′-OH), 4.34 (1H, m, H-3′), 3.79 (1H, m, H-4′), 3.41 (2H, m, H-5′), 2.67 (2H, t, ³J=6.9 Hz, α-CH₂), 2.34 and 2.14 (2H, m, 2-H′a and 2-H′b), 1.67 (2H, m, CH₂), 1.51-1.32 (4H, m, CH₂), 0.84 (3H, t, ³J=6.9 Hz, CH₃). ¹³C-NMR (d₆-DMSO; 75 MHz): 13.2 (CH₃), 20.1, 22.3, 27.9, 28.4, (C₄H₈), 41.3 (C-2′), 62.6 (C-5′), 71.8 (C-3′), 83.4, 86.4 (C-1′, C-4′), 100.4 (C-5), 107.4 (C-4a), 125.4 (C—H_(b)), 127.4 (ipso-C), 131.8 (C—H_(a)), 138.5 (C-4), 141.3 (para-C), 154.6 (C-6), 161.1 (C-2), 170.9 (C-7a).

EXAMPLE 4 Preparation of 3-(2-′deoxy-β-D-ribofuranosyl)-6-(4-n-hexylphenyl)-2,3dihydrofuro-[2,3-d]pyrimidin-2-one

The above general procedure was carried out using 4-n-hexyl-phenylacetylene (1.25 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-hexylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (124 mg, 13%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.85 (1H, s, H-4), 7.53 (2H, H_(a)) −7.29 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.23(1H, s, H-5), 6.24 (1H, dd, ³J=6.15 Hz, H-1′), 5.58 (1H, d, ³J=4.0 Hz, 3′-OH), 5.29 (1H, t, 3J=5.01 Hz, 5′-OH), 4.54 (1H, m, H-3′), 3.79 (1H, m, H-4′), 3.51 (2H, m, H-5′), 2.72 (2H, t,³J=6.9 Hz, α-CH₂), 2.31 and 2.10 (2H, m, 2-H′a and 2-H′b), 1.62 (2H, m, CH), 1.42-1.22 (6H, m, CH₂), 0.87 (3H, t, ³J=6.9 Hz, CH₃). ¹³C-NMR (d₆-DMSO; 75 MHz): 13.2 (CH), 20.1, 22.3, 27.9, 29.5, 30.2 (C₅H₁₀), 41.6 (C-2′), 62.3 (C-5′), 769.8 (C-3′), 83.5, 88.7 (C-1′, C-4′), 99.1 (C-5), 107.2 (C-4a), 124.3 (C—H_(b)), 126.4 (ipso-C), 129.3 (C—H_(a)), 138.5 (C-4), 141.2 (para-C), 154.6 (C-6), 160.9 (C-2), 171.3 (C-7a).

EXAMPLE 5 Preparation of 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-heptylphenyl)-2,3-dihydrofuro-[2,3-4]pyrimidin-2-one

The above general procedure was carried out using 4-n-heptyl-phenylacetylene (1.25 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-heptylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (129 mg, 13%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.91 (1H, s, H-4), 7.62 (2H, H_(a)) −7.35 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.26 (1H, s, H-5), 6.28 (1H, dd, ³J=6.17 Hz, H-1′), 5.62 (1H, d, ³J=4.1 Hz, 3′-OH), 5.32 (1H, t, ³J=5.12 Hz, 5′-OH), 4.52 (1H, m, H-3′), 3.81 (1H, m, H-4′), 3.62 (2H, m, H-5′), 2.71 (2H, t, ³J=6.9 Hz, α-CH₂), 2.35 and 2.14 (2H, in, 2-H′a and 2-H′b), 1.59 (2H, m, CH₂), 1.48-1.21 (8H, m, CH₂), 0.82 (3H, t, ³J=6.9 Hz, CH₃). ¹³C-NMR (d₆-DMSO; 75 MHz): 13.2 (CH), 20.1, 22.3, 27.9, 28.5, 29.5, 30.2 (C₆4), 41.6 (C-2′), 61.5 (C-5′), 69.8 (C-3′), 87.9, 88.5 (C-1′, C-4′), 99.1 (C-5), 107.2 (C-4a), 124.3 (C—H_(b)), 126.2 (ipso-C), 129.3 (C—H_(a)), 138.2(C-4), 144.2 (para-C), 154.6 (C-6), 160.7 (C-2), 170.6 (C-7a).

EXAMPLE 6 Preparation of 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-octylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The above general procedure was carried out using 4-n-octyl-phenylacetylene (1.45 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-octylphenyl)-2,3-dihydrofuro[2,3-d]pyrimidin-2-one (111 mg, 11%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.92 (1H, s, H-4), 7.61 (2H, H_(a)) −7.33 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.25 (1H, s, H-5), 6.21 (1H, dd, ³J=6.19 Hz, H-1′), 5.59 (1H, d, ³J=4.1 Hz, 3′-OH), 5.272 (1H, t, ³J=5.12 Hz, 5′-OH), 4.39 (1H, m, H-3′), 3.75 (1H, m, H-4′), 3.62 (2H, m, H-5′), 2.71 (2H, t, ³J=6.9 Hz, α-CH₂), 2.34 and 2.13 (2H, m, 2-H′a and 2-H′b), 1.61 (2H, m, CH₂), 1.51-1.19 (10H, m, CH₂), 0.82 (3H, t, ³J=6.9 Hz, CH₃). ¹³C-NMR (d₆-DMSO; 75 MHz): 13.2 (CH₃), 20.1, 21.39, 22.3, 27.9, 28.5, 29.5, 30.2 (C₇H₁₄), 41.7 (C-2′), 61.1 (C-5′), 69.8 (C-3′), 87.9, 88.7 (C-1′, C-4′), 99.0 (C-5), 107.2 (C-4a), 124.8 (C—H_(b)), 126.2 (ipso-C), 129.3 (C—H_(a)), 138.2 (C-4), 144.2 (para-C), 154.2 (C-6), 160.7 (C-2), 171.6 (C-7a).

EXAMPLES 7 TO 10 AND 13

The above general procedure was carried out using the appropriate starting materials to produce each of the following respective compounds :

Example 7 3-(2′-deoxy-β-D-ribofuranosyl)-6-(phenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one Example 8 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-methylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one Example 9 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-ethylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one Example 10 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-fluorophenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one Example 13 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-phenylphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one General Procedure for the Preparation of 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-alkoxyphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one and 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-halophenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one Analogues

To a stirred solution of 5-iodo-2′-deoxyuridine (800 mg, 2.26 mmol) in anhydrous dimethylformamide (8 ml), was added diisopropylethylamine (584 mg, 0.8 ml, 4.52 mmol), the 4-n-alkoxy-phenylacetylene or 4-n-halo-phenylacetylene (6.76 mmol), tetrakis(triphenylphosphine)palladium (0) (261 mg, 0.266 mmol) and copper (I) iodide (86 mg, 0.452 mmol). The mixture was stirred for 18 hours, at room temperature, under a nitrogen atmosphere, after which time tlc (ethyl acetate/methanol 9:1), showed complete conversion of the starting material. Copper (I) iodide (80 mg, 0.40 mmol), triethylamine (15 ml) and methanol (20 ml) were then added to the mixture, which was subsequently refluxed for 4 hours. The reaction mixture was then concentrated in vacuo, and the resulting residue was dissolved in dichloromethane and methanol (1:1) (6 ml), and an excess of Amberlite IRA-400 (HC03-form) was added and stirred for 30 minutes. The resin was filtered and washed with methanol, and the combined filtrate was evaporated to dryness. The crude product was purified by flash column chromatography (initial eluent:ethyl acetate, followed by ethyl acetate/methanol (9:1). The appropriate fractions were combined and the solvent removed in vacuo, to give the pure product.

EXAMPLE 11 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-chlorophenyl)-[2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The procedure was carried out using 4-chlorophenylacetylene (0.92 g, 6.76 mmol which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-chlorophenylacetylene)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (474 mg, 58%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.91 (1H, s, H-4), 7.88 (2H, H_(a)) −7.57 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.37 (1H, s, H-5), 6.19 (1H, dd, ³J=6.17 Hz, H1′), 5.35 (1H, d, ³J=4.1 Hz, 3′-OH), 5.24 (1H, t, ³J=5.12 Hz, 5′-OH), 4.26 (1H, m, H-3′), 3.95 (1H, m, H-4), 3.70 (2H, m, H-5′), 2.41 and 2.13 (2H, m, 2-H′a and 2-H⁴⁰b). ¹³CNMR (d₆-DMSO; 75 MHz): 41.6 (C-2′), 60.9 (c-5′), 69.8 (C-3′), 88.0, 88.5, (C-1′, C-4′), 100.8 (C-5), 107.0 (C-4a), 126.6 (C-Hb), 127.6 (ipso-C), 129.6 (C-Ha), 134.2 (C-4), 152.8 (para-C), 154.1 (C-6), 161.2 (C-2), 171.8 (C-7a). MS (ES⁺) m/e 385 (MNa⁺, 100%), 269 (baseNa⁺,

EXAMPLE 12 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-bromophenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The procedure was carried out using 4-bromophenylacetylene (1.22 g, 6.76 mmol), which gave 3-(2¹-deoxy-β-D-ribofuranosyl)-6-(4-bromophenylacetylene)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (174 mg, 19%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.88 (1H, s, H-4), 7.78 (2H, H_(a)) −7.66 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.34 (1H, s, H-5), 6.14 (1H, dd, ³J=6.17 Hz, H1′), 5.31 (1H, d, ³J=4.1 Hz, 3′-OH), 5.19 (1H; t, ³J=5.12 Hz, 5′-OH), 4.65 (1H, m, H-3′), 3.92 (1H, m, H-4), 3.67 (2H, m, H-5′), 2.48 and 2.19 (2H, m, 2-H′a and 2-H′b). ¹³CNMR (d₆-DMSO; 75 MHz): 41.6 (C-2′), 60.9 (c-5′), 69.8 (C-3′), 88.1, 88.5, (C-1′, C-4′), 100.9 (C-5), 107.0 (C-4a), 122.9 (C-Hb), 126.8 (ipso-C), 127.9 (C-Ha), 139.0 (C-4), 152.8 (para-C), 154.1 (C-6), 160.9 (C-2), 171.3 (C-7a). MS (ES⁺) m/e 429 (MNa⁺, 100%), 431 (MNa⁺, 100%), 313 (baseNa⁺, 25%), 315 (baseNa⁺, 25%). Accurate mass: C₁₇H₁₅N₂O₅ ⁷⁹BrNa requires: 429.0062; found: 429.0061; C₁₇H₁₅N₂O₅ ⁸¹BrNa requires 431.0042; found: 431.0052. Found: C, 49.89%; H, 3.88%; N, 6.63%. C₁₇H₁₅BrN₂O₅.0.5H₂Orequires: C, 49.04%; H, 3.88%, N, 6.73%.

EXAMPLE 14 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-methoxyphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The procedure was carried out using 4-methoxyphenylacetylene (0.893 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-methoxyphenylacetylene)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (353 mg, 43%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.81 (1H, s, H-4), 7.77 (2H, H_(a)) −7.12 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.06 (1H, s, H-5), 6.20 (1H, dd, ³J=6.17 Hz, H1′), 5.32 (1H, d, ³J=4.1 Hz, 3′-OH), 5.20 (1H, t, ³J=5.12 Hz, 5′-OH), 4.05 (1H, m, H-3′), 3.93 (1H, m, H-4′), 3.83 (3H, s, OCH₃), 3.69 (2H, m, H-5′), 2.39 and 2.12 (2H, m, 2-H′a and 2-H′b). ¹³CNMR (d₆-DMSO; 75 MHz): 41.6 (C-2′), 55.7 (OCH₃), 61.0 (C-5′), 69.8 (C-3′), 88.5, 87.9 (C-1′, C-4′), 97.7 (C-5), 107.5 (C-4a), 114.9 (C-Hb), 121.3 (ipso-C), 126.6 (C-Ha), 137.6 (C-4), 154.1 (para-C), 154.2 (C-6), 160.5 (C-2), 171.4 (C-7a). MS (ES⁺) m/e 381 (MNa⁺, 100%), 265 (baseNa⁺, 20%), Accurate mass: C₁₈H₁₈N₂O₆Na requires: 381.1063; found: 381.1069; Found: C, 59.83%; H, 5.29%; N, 7.83%. C₁₈H₁₈N₂O₆ requires: C, 60.33%; H, 5.06%, N, 7.82%.

EXAMPLE 15 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4ethoxyphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The procedure was carried out using 4-ethoxyphenylacetylene (0.988 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-ethoxyphenylacetylene)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (256 mg, 30%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.80 (1H, s, H-4), 7.77 (2H, H_(a)) −7.11 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.06 (1H, s, H-5), 6.19 (1H, dd, ³J=6.17 Hz, H1′), 5.32 (1H, d, ³J=4.1 Hz, 3′-OH), 5.20 (1H, t, ³J=5.12 Hz, 5′-OH), 4.26 (1H, m, H-3′), 4.08 (2H, q, OCH₂), 3.92 (1H, m, H-4), 3.69 (2H, m, H-5′), 2.40 and 2.09 (2H, m, 2-H′a and 2-H′b), 1.35 (3H, t, CH₃) ¹³CNMR (d₆-DMSO; 75 MHz): 14.9 (CH₃), 41.6 (C-2′), 61.0 (C-5′), 63.7 (OCH₂), 69.8 (C-3′), 87.9, 88.5, (C-1′, C-4′), 97.6 (C-5), 107.5 (C-4a), 115.3 (C-Hb), 121.1 (ipso-C), 126.6 (C-Ha), 137.6 (C-4), 154.1 (para-C), 154.3 (C-6), 159.8 (C-2), 171.4 (C-7a). MS (ES⁺) m/e 395 (MNa⁺, 100%), 279 (baseN⁺, 20%). Accurate mass: C₁₉H₂₀N₂O₆Na requires: 395.1219; found: 395.1216. Found: C, 60.97%; H, 5.67%; N, 7.29%. C₁₉H₂₀N₂O₆ requires: C, 61.28%; H, 5.41%, N, 7.52%

EXAMPLE 16 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-propoxyphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The procedure was carried out using 4-n-propoxyphenylacetylene (1.08 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-propoxyphenytacetylene)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (552 mg, 59%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.80 (1H, s, H-4), 7.78 (2H, H_(a)) −7.12 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.07 (1H, s, H-5), 6.19 (1H, dd, ³J=6.17 Hz, H1′), 5.31 (1H, d, ³J=4.1 Hz, 3′-OH), 5.19 (1H, t, ³J=5.12 Hz, 5′-OH), 4.26 (1H, m, H-3′), 4.00 (2H,t, OCH₂), 3.98 (1H, m, H-4′), 3.67 (2H, m, H-5′), 2.40 and 2.12 (2H, m, 2-H′a and 2-11′b), 1.80 (2H, m, CH₂), 1.03 (3H, t, CH₃) ¹³CNMR (d₆-DMSO; 75 MHz): 10.7 (CH₃), 22.3 (CH₂), 41.6 (C-2′), 61.0 (C-5′), 69.5 (OCH₂), 69.8 (C-3′), 87.9, 88.5, (C-1′, C-4′), 97.6(C-5), 107.5 (C-4a), 115.4 (C-Hb), 121.1 (ipso-C), 126.6 (C-Ha), 137.6 (C-4), 154.1 (para-C), 154.3 (C-6), 160.0 (C-2), 171.3 (C-7a). MS (ES⁺) m/e 409 (MNa⁺, 100%), 293 (baseNa⁺, 25%). Accurate mass: C₂₀H₂₂N₂O₆Na requires: 409.1376; found: 409.1374; Found: C, 61.97%; H, 5.67%; N, 7.29%. C₁₉H₂₀N₂O₆ requires: C, 62.17%; H, 5.74%, N, 7.25%.

EXAMPLE 17 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-pentoxyphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The procedure was carried out using 4-n-pentoxyphenylacetylene (1.27 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-pentoxyphenylacetylene)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (503 mg, 53%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.80 (1H, s, H-4), 7.78 (2H, H_(a)) −7.07 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.04 (1H, s, H-5), 6.20 (1H, dd, ³J=6.17 Hz, H1′), 5.31 (1H, d, ³J=4.1 Hz, 3′-OH), 5.19 (1H, t, ³J=5.12 Hz, 5′-OH), 4.27 (1H, m, H-3′), 4.02 (2H, t, OCH₂), 3.93 (1H, m, H-4), 3.69 (2H, m, H-5′), 2.39 and 2.13 (2H, m, 2-H′a and 2-H′b), 1.73 (2H, m, CH₂), 1.38 (4H, m, 2CH₂), 0.91 (3H, t, CH₃). ¹³CNMR (d₆-DMSO; 75 MHz): 14.3 (CH₃), 22.2 (CH₂CH₃), 28.0 (CH₂CH₂CH₃), 28.6 (CH₂CH₂CH₂CH₃) 41.6 (C-2′), 61.0 (C-5′), 68.0 (OCH₂), 69.8 (C-3′), 87.9, 88.5, (C-1′, C-4′), 97.6 (C-5), 107.5 (C-4a), 115.4 (C-Hb), 121.1 (ipso-C), 126.6 (C-Ha), 137.6 (C-4), 154.1 (para-C), 154.3 (C-6), 160.0 (C-2), 171.4 (C-7a). MS (ES⁺) m/e 437 (MNa⁺, 100%), 321 (baseNa⁺, 20%). Accurate mass: C₂₂H₂₆N₂O₆Na requires: 437.1689; found: 437.1695. Found: C, 60.07%; H, 6.63%; N, 6.27%. C₂₂H₂₆N₂O₆.1.5H₂O requires: C, 59.85%; H, 6.62%, N, 6.35%.

EXAMPLE 18 3-(2′-deoxy-β-D-ribofuranosyl)-6(4-n-hexoxyphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The procedure was carried out using 4-n-hexoxyphenylacetylene (1.37 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-hexoxyphenylacetylene)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (540 mg, 55%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.80 (1H, s, H-4), 7.77 (2H, H_(a)) −7.11 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.07 (1H, s, H-5), 6.20 (1H, dd, ³J=6.17 Hz, H1′), 5.31 (1H, d, ³J=4.1 Hz, 3′-OH), 5.19 (1H, t, ³J=5.12 Hz, 5′-OH), 4.26 (1H, m, H-3′), 4.02 (2H, t, OCH₂), 3.94 (1H, m, H-4), 3.70 (2H, m, H-5′), 2.41 and 2.12 (211, m, 2-H′a and 2-H′b), 1.73 (2H, m, OCH₂CH₂), 1.43 (2H, t, OCH₂CH₂CH₂), 1.32 (4H, m, 2CH₂), 0.89 (3H, t, CH₃). ¹³CNMR (d₆-DMSO; 75 MHz): 14.3 (CH₃), 22.4 (CH₂CH₃), 25.5 (CH₂CH₂CH₃), 28.9 (CH₂CH₂CH₂CH₃), 31.3 (CH₂CH₂CH₂CH₂CH₃), 41.6 (C-2′), 60.9 (C-5′), 68.0 (OCH₂), 69.8 (C-3′), 88.0, 88.5, (C-1′, C-4′), 100.8 (C-5), 107.0 (C-4a), 115.3 (C-Hb), 121.1 (ipso-C), 126.6 (C-Ha), 137.5 (C-4), 154.2 (para-C), 154.5 (C-6), 161.2 (C-2), 171.8 (C-7a). MS (ES⁺) m/e 451 (MNa⁺, 100%), 335 (baseNa⁺, 10%). Accurate mass: C₂₃H₂₈N₂O₆Na requires: 451.1845; found: 451.1843. Found: C, 64.28%; H, 6.74%; N, 6.35%. C₂₃H₂₈N₂O₆ requires: C, 64.47%; H, 6.59%, N, 6.54%.

EXAMPLE 19 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-heptoxyphenyl)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one

The procedure was carried out using 4-n-heptoxyphenylacetylene (1.46 g, 6.76 mmol), which gave 3-(2′-deoxy-β-D-ribofuranosyl)-6-(4-n-heptoxyphenylacetylene)-2,3-dihydrofuro-[2,3-d]pyrimidin-2-one (193 mg, 19%), after purification by column chromatography.

¹H-NMR (d₆-DMSO; 300 MHz); 8.80 (1H, s, H-4), 7.78 (2H, H_(a)) −7.11 (2H, H_(b)) (AB system, ³J=7.89 Hz, ⁴J=2.3 Hz), 7.07 (1H, s, H-5), 6.20 (1H, dd, ³J=6.17 Hz, H1′), 5.31 (1H, d, ³J=4.1 Hz, 3′-OH), 5.19 (1H, t, ^(s)J=5.12 Hz, 5′-OH), 4.26 (1H, m, H-3′), 4.02 (2H, t, OCH₂),4.00 (1H, m, H-4′), 3.92 (2H, m, H-5′), 2.51 and 2.09 (2H, m, 2-H′a and 2-H′b), 1.73 (2H, m, OCH₂CH₂), 1.33 (8H, m, 4CH₂), 0.87 (3H, t, CH₃). 13CNMR (d₆-DMSO; 75 MHz): 14.3 (CH₃), 22.4 (CH₂CH₃), 25.8 (CH₂CH₂CH₃), 28.8 (CH₂CH₂CH₂CH₃), 31.6 (CH₂CH₂CH₂CH₂CH₃), 33.7 (CH₂CH₂CH₂CH₂CH₂CH₃), 41.6 (C-2′), 61.2 (C-5′), 68.8 (OCH₂), 69.8 (C-3′), 88.1, 88.7, (C-1′, C-4′), 99.7 (C-5), 107.0 (C-4a), 115.3 (C-Hb), 121.1 (ipso-C), 126.8 (C-Ha), 137.5 (C-4), 154.2 (para-C), 154.5 (C-6), 161.2 (C-2), 171.8 (C-7a). MS (ES⁺) m/e 465 (MNa⁺, 100%), 349 (baseNa⁺, 10%). Accurate mass: C₂H₃₀N₂O₆Na requires: 465.2002; found: 465.2001. Found: C, 62.74%; H, 7.08%; N, 6.06%. C₂₄H₃₀N₂O₆.H₂O requires: C, 62.59%; H, 7.01%, N, 6.08%. 10%). Accurate mass: C₁₇H₁₅N₂O₅ClNa requires: 385.0567; found: 385.0575. Found: C, 56.02%; H, 4.39%; N, 7.67%. C₁₇H₁₅ClN₂O₅ requires: C, 56.29%; H, 4.17%, N, 7.72%.

Biological Activity

The compounds of each the present examples 1 to 19 were tested in vitro in tissue culture assays for potent anti-viral action with respect to varicella zoster virus (VZV). The results in terms of EC50 which was defined as the drug concentration (in yM) required to reduce virus-induced cytopathicity by 50%, are given in the Table below. The column titles in the table stand for :

R₉, for compounds embodying the present invention, is Ar as in formula I above.

EC50 VZV OKA yM stands for “50% effective concentration” and is the compound concentration required to reduce viral plaque formation after 5 days by 50%, compared to an untreated control, using OKA viral strain.

EC50 VZV YS AM stands for “50% effective concentration” and is the compound concentration required to reduce viral plaque formation after 5 days by 50%, compared to untreated control, using YS viral strain.

EC50 VZV TK'07 M stands for “50% effective concentration” and is the compound concentration required to reduce viral plaque formation after 5 days by 50%, compared to untreated control, using viral strain 07 ; TK deficient.

EC50 VZV TK-YS uM stands for “50% effective concentration” and is the compound concentration required to reduce viral plaque formation after 5 days by 50%, compared to untreated control, using viral strain YS ; TK deficient.

MCC AM is the minimum cytotoxic concentration to human embryonic lung cells. CC50 AM is 50% cytotoxic concentration to human embryonic lung cells. Further details of the methodology employed can be found in McGuigan et al. J. Med. Chem., 1999, 42, 4479-4484.

TABLE EC50 EC50 EC50 VZV EC50 VZV VZV OKA VZV YS TK-07 TK-YS MCC CC50 Example R μM μM μM μM μM μM  7 —C₆H₅ <0.5 <0.5 >200 162 >200 >200  8 —pC₆H₄—CH₃ <0.5 <0.5 103 >200 >200 >200  9 —pC₆H₄—C₂H₅ <0.5 <0.5 >50 >50 200 123  1 —pC₆H₄—nC₃H₇ 0.011 0.009 >50 >20 ≧50 188  2 —pC₆H₄—nC₄H₉ 0.0032 0.0002 13 >20  3 —pC₆H₄—nC₅H₁₁ 0.00006 0.00005 >20 >5  4 —pC₆H₄—nC₆H₁₃ 0.00011 0.00007 >5 >5  5 —pC₆H₄—nC₇H₁₅ 0.0034 0.0009 >5 >5 5 18  6 —pC₆H₄—nC₈H₁₇ 0.015 0.005 >20 >20 ≧20 >200 Acyclovir 2.9 1 74 125 >200 >200 BVDU 0.003 Ex2 WO —nC₁₀H₂₁ 0.015 0.008 >50 >50 >50 >50 98/49177 10 —pC₆H₄—F >50 >50 >50 >50 200 171 11 —pC₆H₄—Cl 0.1 0.08 >20 >20 ≧20 >200 12 —pC₆H₄—Br 0.29 0.2 >5 >5 >2 96 13 —pC₆H₄—C₆H₄ 0.031 0.032 >5 >5 >200 >200 14 —pC₆H₄—OCH₃ 0.05 0.05 >50 >50 200 >200 15 —pC₆H₄—OC₂H₅ 0.01 0.01 50 >50 200 >200 16 —pC₆H₄—OnC₃H₇ 0.002 0.002 11 >50 ≧200 >200 17 —pC₆H₄—OnC₅H₁₁ 0.002 0.002 3.7 >20 >50 >200 18 —pC₆H₄—OnC₆H₁₃ 0.002 0.002 >5 >20 >20 >200 19 —pC₆H₄—OnC₇H₁₅ 0.002 0.002 >50 >20 ≧50 >200

As can be seen from the data contained in the above Table, compounds comprising Examples 2 to 5 and 15 to 19 embodying the present invention demonstrate increased potency having regard to the known potency of the prior art compounds contained in the Table. Optimum compounds can be seen to those of Examples 2 to 5 and 16 to 19 exemplifying the present invention. Compounds displaying the greatest increase in potency can be seen to be those of Examples 3 and 4 of the present invention.

Increased potency of the compounds of the present invention permit effective reduced doses to be administered to a patient in need thereof. Reduced dosage, either in terms of the number of doses required or the quantity required per dose or both, can enhance the convenience to, and hence compliance by, the patient and can permit a commensurate reduction in likely host toxicity and any side effects.

Compounds comprising Examples 1, 6 and 11 to 14 demonstrate comparable potency having regard to the known potency of the prior art compounds contained in the Table. 

What is claimed is:
 1. A compound having the formula:

wherein Ar is an optionally substituted aromatic ring system comprising one six-membered aromatic ring or two fused six-membered aromatic rings; R₈ and R₉ are each independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, halogen, amino, alkylamino, dialkylamino, nitro, cyano, alkoxy, aryloxy, thiol, alkylthiol, arylthiol, and aryl; Q is selected from the group consisting of O, S, and CY₂, where each Y may be the same or different and is selected from the group consisting of H, alkyl, and halogen; X is selected from the group consisting of O, NH, S, N-alkyl, (CH₂)_(m) where m is 1 to 10, and CY₂ where each Y may be the same or different and is selected from the group consisting of hydrogen, alkyl and halogen; Z is selected from the group consisting of O, S, NH, and N-alkyl; U″ is H and U′ is selected from H and CH₂T, or U′ and U″ are joined so as to form a ring moiety including Q wherein U′-U″ together is respectively selected from the group consisting of —CTH—CT′T″ and —CT′=CT′-, so as to provide ring moieties selected from the group consisting of:

wherein: T is selected from the group consisting of OH, H, halogen, α-alkyl, α-acyl, α-aryl, CN, NH₂, and N₃; T′ is selected from the group consisting of H and halogen and, where more than one T′ is present, they may be the same or different; T″ is selected from the group consisting of H and halogen; and W is selected from the group consisting of H, a phosphate group and a pharmacologically acceptable salt, derivative or pro-drug thereof; with the provisos that: (1) when T is OAc and T′ and T″ are present and are H, Ar is not 4-(2-benzoxazolyl)phenyl; and (2) when Q, X and Z are each O, and R₈, R₉, T′, T″ and W are each H and T is OH or O-acyl, Ar is: one six-membered carbocyclic aromatic ring substituted by one or more moieties independently selected from the group consisting of alkyl, aryl, cycloalkyl, chlorine, bromine, iodine, cyano, alkylamino, dialkylamino, alkoxy, aryloxy, alkylthio, and arylthio, any of which alkyl, cycloalkyl or aryl moieties may be substituted by one or more members selected from the group consisting of chlorine, bromine, iodine, CN, CO₂—C₁-C₆ alkyl, CONH₂, CONH—C₁-C₆ alkyl, SR, S—C₁-C₆ alkyl, and NO₂; one six-membered aromatic ring system which contains one, two, three or four hetero atoms and which ring system may be optionally substituted; or two fused six-membered aromatic rings, which may be optionally substituted.
 2. A pharmaceutical composition comprising a compound of claim 1 and a pharmaceutically acceptable excipient.
 3. A method of prophylaxis or treatment of a viral infection comprising administering to a patient in need of such treatment an effective dose of a compound of claim
 1. 